1. Field of the Invention
The present invention relates to a pulsimeter and particular to a pulsimeter having a photosensor for measuring, by a photoelectric conversion system, the pulse of a person to be examined.
2. Description of the Prior Art
Pulsimeters in the prior art have various methods for measuring pulse. Particularly, pulsimeters of a photoelectric conversion system have been proposed as this system enables measurement without externally hurting the examined human body.
Such a pulsimeter of the photoelectric conversion system measures the pulse by utilizing light transmittance through the human body, which changes according to change in bloodstream in capillaries because the bloodstream in the blood vessel periodically changes according to pulsation of the heart.
FIG. 1 is a block diagram showing an overall construction of such a conventional pulsimeter of the photoelectric conversion system.
Referring to FIG. 1, an electric signal generated in a light emitting portion drive circuit 1 contained in the main body of the pulsimeter is transmitted to a pulse sensor portion 2 including a photosensor through a cord, to cause a light emitting portion 3 of a light emitting diode to emit light. The photosensor 2 has the light emitting diode 3 and a photodiode 4 as a light receiving portion facing each other. The photosensor 2 is used in a manner in which an earlobe or finger of a person to be examined is held therebetween. The reason for using the photosensor 2 for such an end part of a human body is that little error occurs in measurement of such an end part which is hardly affected by movements of the muscle and the thickness of which is hardly changed. The light transmitted through the earlobe or the like is received by the photodiode 4, where it is converted to an electric signal according to the quantity of received light. The electric signal is applied to a filter circuit 7 contained in the main body of the pulsimeter through a cord. The electric signal, from which a DC component caused by unnecessary light such as external light is removed in the filter circuit 7, is then AC-amplified in an AC amplifier 9 and thus pulse-shaped. A changing cycle of the AC-amplified signal output is measured by a pulse cycle measuring device 10 and then a pulse rate is evaluated by a CPU 11, whereby the evaluated value is indicated on a display device 12.
In such a conventional pulsimeter as described above, the pulse sensor portion including the photosensor, and the main body including a detection circuit, an evaluation circuit and the like are usually connected through a cord for convenience of use. Consequently, the cord is bent or pulled dependent on the state of use or the frequency of use and as a result breaking of the core wire, short circuit or the like might occur.
However, if a trouble of the core wire occurs, it sometimes happens that a pulse rate is represented as having been measured on a display device although it is indicated by unusual numerals. Accordingly, it is sometimes difficult for the operator to judge whether the pulse rate represented by unusual numerals is caused by any trouble in the core wire or any disorder in the examined person. Therefore, it is likely to occur that such an erroneous pulse rate is treated as data of the examined person.